Liquid blenders for the fertilizer industry are well known in the prior art. These commercial blenders consist of a large vertically-oriented tank mounted on scales for carefully measuring the desired ingredients placed into the tank in a given sequence. A vertical shaft is journaled in suitable bearings, substantially coaxially of the tank, and is driven by an electric motor and suitable belts mounted above the tank. An impeller is mounted on the bottom end of the drive shaft for providing the desired mixing action within the funnel-shaped bottom portion of the tank. The impeller may consist of a stirrer (resembling a "propeller") or a fan wheel or a circular plate having vanes and apertures. An external pump, together with respective conduits, flexible couplings and valves, are necessary to draw off the mixture and recirculate it back into the tank. Whenever appropriate, the pump also draws off the mixture and pumps it into storage tanks or truck-driven trailer tanks.
A mixing apparatus having this general configuration is shown, for example, in U.S. Pat. No. 2,706,622 issued in 1955, wherein the impeller consists of a rotating pump wheel having a plurality of circumferentially-spaced radially-directed vanes.
The prior art also includes U.S. Pat. No. 3,263,968 for a "slurry handling apparatus" issued in 1966. In this patent, a buried tank receives manure via a trough in the barn, and a centrifugal pump provides for internal circulation and external discharge. The pump has a rotary impeller with radially-extending vanes. A vertically-mounted electric motor provides power to the pump via a V-belt drive.
On the other hand, conventional slurry pumps (per se) are well-known in the prior art. These pumps are intended for pumping a variety of liquids and materials, such as sludge, and generally consist of a plurality of parallel spaced-apart discs suitably mounted together and driven in unison. Examples are shown in U.S. Pat. No. 1,061,142 issued in 1913 and U.S. Pat. No. 2,087,834 issued in 1937, the latter constituting a "fluid impeller and turbine" and having a series of annular plates provided with internal openings of progressively increasing diameter.
Despite these isolated disclosures in the prior art, no one to date has conceived of the unique combination of a specially-designed fluid pump (similar to a conventional slurry pump) in a high-speed fluid blender especially adapted for the liquid fertilizer industry.